Thanks for that analysis...i worked from the bottom up and wrote down the forces on each of the line segments, but couldn't figure out the short anchor section on the top, that you labeled 3/4T. If you look at my picture of the rings, you can see that I omitted that 3/4T section, and tied the short T/4 line directly to the pulley.

The reason for including the short anchor section on the top, is because that is how it appears in Zeeko's Ultimate Bar User Guide. But I agree, you can tie the short T/4 line directly to the pulley. That is what I have done on my configuration. Instead of using a pulley, or a round steel ring as you have done, I used a D ring from a worn out harness.

I think in my particular case the weakest point will be where the double powerline attaches to a ring on the QR/CL, because this ring is made of smaller gauge stainless steel than the other rings. If that happens, my kite will be suspended on the rear lines. Fortunately, this is one area where the wear on the line will be distributed over perhaps 20 or 30cm, as you adjust the depower. It will also be very easy to inspect, because this ring is as exposed as the others.

I have not yet ventured onto the water with my system, because yesterday the wind was too light. Slipping to full power might become an issue when the depower line is wet. The fact that you and I use rings instead of pulleys may be of advantage here, because the extra friction may prevent slipping.

OK...now I am getting serious...data from my "test rig" will be posted in a day or so.

I am measuring both the "tension" in each 'leg' of the system, and also the "force" needed to change the position of each 'leg'. Any suggestions would be appreciated.

Here are some pictures:

ZigZag,

I bet you will be surprized that the system will not shorten, even if the rope is wet and you put some extreme force on the system... I know, I was. However, if you want to pretty much eliminate the "friction" in the system, at home, high and dry, you could (1) wet the rope in your sink and (2) grease the rope with dish soap.

Well....I'm sorry to dissapoint.... It isn't quite a magic as I thought.

I have done a bit more tinkering.Built a system with low friction ball race pulleys.

Now it behaves exactly how I originally suspected.ie Put tension on bottom pulley and middle pulley (or ring in the diagram) shoots up to collide with the top pulley (ie system goes to its maximum length).

It seems that the system I previously built with rings just relied on friction. Obviously, it can be made to work (Zeeko made it work) but it isn't the magically stable sytem that I thought it was.

faklord wrote:Well....I'm sorry to dissapoint.... It isn't quite a magic as I thought.

I have done a bit more tinkering.Built a system with low friction ball race pulleys.

Now it behaves exactly how I originally suspected.ie Put tension on bottom pulley and middle pulley (or ring in the diagram) shoots up to collide with the top pulley (ie system goes to its maximum length).

It seems that the system I previously built with rings just relied on friction. Obviously, it can be made to work (Zeeko made it work) but it isn't the magically stable sytem that I thought it was.

I'm out.

Faklord,

I am impressed with your experiments...first with the elastic and then with the low friction pulleys. Nice job. I wish I had some pulleys like that...ceramic? Where can I get some?

I guess that answers the question of how the Zeeko system was created. It must have been by trial and error to determine that it would work with the kind of forces generated by kiters and kites. If he drew a force diagram, he probably would have concluded that the system would not work. I do believe that there is a lot of friction in the system, using 3 rings. My present experiment uses 3 old pulleys from a kite bridle and a windsurfing downhaul hook, and I have been impressed by the range of readings I have been getting, due to "sticktion" (getting the pulleys to initially turn). The forces that I have been recording show a decrease in force of a couple pounds, once the pulleys start turning. I may try to calculate the force of friction of each pulley (or better yet of the rings, that I will actually be using, in my set-up) by measureing the tension of each leg on both sides of the pulley, while the system is under load. I have been using 40 pounds of force on the system... but 40 pounds of force is not much compared to the hundreds of pounds of force that a kiter will actually apply to the system...but my fish scale only goes up to 50 pounds.

So, a preliminary conclusion, as to why the total length of the system does not shorten in kiteboarding application practice, would be that: as the kiter and kite start to exert "extreme" force on the system...the friction on the rings and pulley also becomes more "extreme", and resists the natural movement of the system to acheive neutral stability, where the 2 top rings would be drawn together.

So, I guess we may need clarification of the force diagram, showing unbalanced forces.

Very interesting. I wonder what would break or slide first with the Zeeko set-up, if the system was taken to failure?...I bet this could be done with a manual 3 ton "come-along" hand winch.

It will be fun to find out what real-life kiteing situation will exert enough force on the system to cause the system to either break some component... or will cause the ring to slip and thereby, cause the total line length to elongate.

I would guess that this Zeeko system will be popular, and will get some real Beta Testing, by kiters... just like Microsoft products. I will be one of those test crash dummies.

There was enough wind yesterday afternoon to take my home made Zeeko rig onto the water. I flew a very old and patched kite in case of catastrophic failure. Here is a picture of the rig as it came off the water.

Here is a picture of the business end.

And here is a picture of the bottom ring on the CL.

I am pleased to report that the rig worked faultlessly. My two main concerns were slipping under load, and breaking under load, and it did neither of these things. In fact, it was far more stable than my old strap depower, which needs to be re-set a few times in powered conditions due to slipping.

Adjusting the power was very easy. In underpowered conditions, pull in the bar with your right hand, reach above the bar with your left hand and pull down on the left leg as shown on the Zeeko diagram. In overpowered conditions, let out the bar with your left hand, reach below the bar with your right hand and pull on the right leg. Sounds complicated, but in practice it is easy.

Self-landing and self-launching using the tethered system was easier than with my standard strap depower. Normally I pull the depower strap completely before landing. My Zeeko rig does not have a stopper, so the bar goes right to the end of the depower line, and the kite sits with slack back lines.

I realise now that the force diagram I presented earlier is completely wrong. I am sure that tomatkins and Faklord knew this as well, but both of them were far too polite and well-mannered to point it out.

You are much too kind...I found myself "believing" about 3 different versions of diagrams...Faklord is the heroe, in my opinion... he saved me about 4 hours of dinking around with my "test rig".

I bet you will be happier adjusting the system if you tinker up one of these double ball/Prussic knot devices, to grab, and ratchet the line down, in order to depower, below the bar... doesn't take up much room and is simple to make from 2 pastic balls... and protects your hand from getting pinched between the 2 lines, if something unexpected happens to power up the kite.

The only results to report from y "testing" is the hypothesis that there is about 2-3 pounds of friction caused by each of the rings, when the whole system is loaded with a total of 40 pounds load... so I might conclude that at 40 pounds load, it takes between 6 and 9 pounds of friction to keep the system 'stable' and un-balanced... so I guess if this is correct, then you could draw a force diagram, showing an additional 6 to 9 pounds force on one leg of the rope...probably the 'leg' of the rope, which is used to depower the system. I could be wrong...I, like you, am just happy it works. I really appreciated your previous analysis... both you and Faklord (and others) were way ahead of me.

You are much too kind...I found myself "believing" about 3 different versions of diagrams...Faklord is the heroe, in my opinion... he saved me about 4 hours of dinking around with my "test rig".

I bet you will be happier adjusting the system if you tinker up one of these double ball/Prussic knot devices, to grab, and ratchet the line down, in order to depower, below the bar... doesn't take up much room and is simple to make from 2 pastic balls... and protects your hand from getting pinched between the 2 lines, if something unexpected happens to power up the kite.

The only results to report from y "testing" is the hypothesis that there is about 2-3 pounds of friction caused by each of the rings, when the whole system is loaded with a total of 40 pounds load... so I might conclude that at 40 pounds load, it takes between 6 and 9 pounds of friction to keep the system 'stable' and un-balanced... so I guess if this is correct, then you could draw a force diagram, showing an additional 6 to 9 pounds force on one leg of the rope...probably the 'leg' of the rope, which is used to depower the system. I could be wrong...I, like you, am just happy it works. I really appreciated your previous analysis... both you and Faklord (and others) were way ahead of me.

Would it not be advisable to put those red prussic knot/ball above the bar insted? (and naturally a black dito on the left side for power-up).

Here is a question. Does anyone know of a decent chicken loop w/ propper push release that can route the depower line down and back and allow it to slide as is needed for a system like this. I guess I mean are there any others in addition to the Zeeko's. Seems to me, all you really need after that is a couple 1" SS rings and you can throw one of these together on almost any bar.

P.S. I like the doubble ball ratchet adjustment handle above. That seems a nice simple option.

No need for a black one on the other side, ratchet one way to power up and the other to power down.

Run this with a miny 5th line to keep it all leashed in case of a failure and I think this could be a sweet system.

Starsky wrote:Here is a question. Does anyone know of a decent chicken loop w/ propper push release that can route the depower line down and back and allow it to slide as is needed for a system like this. I guess I mean are there any others in addition to the Zeeko's. Seems to me, all you really need after that is a couple 1" SS rings and you can throw one of these together on almost any bar.

P.S. I like the doubble ball ratchet adjustment handle above. That seems a nice simple option.

No need for a black one on the other side, ratchet one way to power up and the other to power down.

Run this with a miny 5th line to keep it all leashed in case of a failure and I think this could be a sweet system.

Youre probably right, no need for the black one. If it doesnt work its easy enough to add one later on. Usually its easier to "pull" then "push" but maybe in this system it its easy enough with just one one "tab".